In the control of the operation of the engines of automotive vehicles, it is common to utilize a temperature sensor in the air cleaner to control the blend of cold and hot air passing to the air cleaner and in turn, the carburetor of the engine. Such temperature sensors are shown in the U.S. Pat. Nos. to Lewis 3,459,163, Kearsley 3,513,817 and Charles 3,744,716.
A problem in connection with the manufacture of such temperature sensors is that they must be calibrated to produce the desired temperature control. During the calibration, the bimetallic element that is usually associated with the temperature sensor is adjusted after which the assembly is completed. During the final assembly, it is possible that the various operations will result in movement with the resultant loss of calibration.
Accordingly, the present invention is directed toward making an air cleaner temperature sensor which will obviate or minimize the possibility of loss of calibration during the final assembly step.
Another problem that arises in connection with prior air cleaner temperature sensors is that they usually modulate the vacuum to a vacuum motor that functions to control the blend of hot and cold air passing to the air cleaner. However, when a full throttle acceleration is made, engine vacuum is zero and the vacuum motor which is being controlled by the vacuum translates to a full cold position regardless of the temperature in the air cleaner. This results in maximum air density and maximum horsepower for a full throttle acceleration. While this is acceptable for an engine at normal operating temperature, full throttle accelerations on a cold engine often cause engine loss due to the increased density of the unheated air causing a leaner mixture below the proper combustion level. It has been found that if the motor that controls the mixture of air is maintained in a position permitting full hot air to pass to the air cleaner during engine warm-up, engine operation is improved. Thus, another aspect of the present invention is to provide an improved separate temperature control check valve in the air cleaner temperature sensor which will function to trap vacuum in the motor that is being controlled resulting in the full hot position of the motor and the associated control regardless of engine vacuum.
Another aspect of the invention is to provide such a device which will trap vacuum which will be progressively dissipated.